In many applications the service provider provides a service to a client via a network. The service provider can have a server offering the services via the network to a client connected to the network. The client can be terminal being connected to a customer premise site which in turn is connected to a central office site by means of a primary network infrastructure such as a fiber or wholesale Ethernet. Several office sites can be connected for example via the Internet to the server of the service provider. The primary infrastructure can consist of one or several links. These links can be constituted by a wireless or wired links such as fibers or cables transporting for example data packets and messages bidirectional between the customer premise site and the central office. Consequently, the client is connected via a primary data path to a server of a service provider. This data path may include one or several physical links or generic data transmission circuitry. The data packets transported via the primary infrastructure comprise header and payload and are transported according to a predetermined protocol. For example, the data packets may comprise Ethernet packets which are transported accordingly to an Ethernet based protocol. The data path between a terminal or client device and the entity providing the service can comprise one or more logical and/or physical connections between the two data endpoints having a direct data connectivity. The data exchange between the two data endpoints is transported with a data rate such as a bit-rate or a data packet rate. Since the traffic flow between the data endpoints varies under changing conditions the associated traffic flows must cope with these changes. Changing conditions can cause variable bit or data packet rates transporting the data via the primary infrastructure.
Furthermore, the bit rate between an uplink and a downlink can be asymmetric and have the same or different changing conditions. It can happen that in the primary data path having one or more physical links a link loss occurs, i.e. a physical link may be interrupted. If the data path only has one physical link this link loss causes a complete interruption of the respective data path. If the data path comprises more than one link the interruption of one physical link will change the bandwidth or data rate of the primary data path transporting bidirectional data between the two endpoints. The service provider often has a service level agreement SLA with the customer guaranteeing the customer to receive services at a certain bandwidth or within a certain time limit.
Consequently, when a link loss in the primary data path occurs it is necessary to shift at least a portion of the data traffic which has been transported via the primary data path to at least one other secondary data path which can also include one or more physical and/or logical links. After initiating a secondary data path the provided bandwidth must be sufficient to provide the client device with the desired service according to the service requirements of the service level agreement SLA between the client and the service provider.
Accordingly, there is a need for a mechanism or method which supplies a flexible backup bandwidth control taking into account changing conditions in the network infrastructure.